I have a fuel pressure gauge in the cabin, so I can see what the fuel pressure is all the time. Stays at a constant 60psi no matter how the truck is running. I have checked for vacuum leaks, probably a total of 5 hours doing it lol .. it doesn't hurt to check more though, I'll look again.

It actually does go into Reduce performance, today I mess with it some more though and it still runs like **** even with TB unplugged (though it prob is suppose to run like **** with TB unplugged lol)

I'm 80% sure it use to not do this. It always seemed to run slow though (it couldn't ever do better than a 14.5 1/4 mile w/ my setup...).


I have been lately seeing oil in my charge pipes, so I reamped my breather system to eliminate any blow by. It still seems to push oil though through the turbo though. The turbo shaft has no play in it at all. Even with MAF cleaned and turbo disconnected, it still does not idle good.

Yeah, it is just the fact that I don't think it use to do this which is preventing me from bothering him about it. After I put the turbo on, I went to school. So I only drove it to school and back (10 min. drive) and I never recalled it doing this. I do recall driving to school a couple times of the final days of the semester and it would idle rough and die when I came to a sudden stop. Since I've been back home and driving it, it gets worse and worse. It really does it bad when it is hot outside and at full temp





example, if I start it up (cold start) it will idle perfectly w/ no misfires. If I let it sit for 20 minutes idling in its own heat it will start to idle rough and misfire (you can hear all the misfires through the exhaust)

 

Now that I think of it, all of this started when it was getting warmer after this last Winter.

I also installed a 4L80E and 3000rpm converter during the winter months. I wonder if this might be the problem? I've been reading high stalled converters can cause rough idle..

 

guys, check this out. I logged the truck while it was idling rough. I logged the current cylinder firing and just a couple other things so I could get a high frame rate. Notice the current cylinder firing tab, half of the cylinders are not even firing.

This leads to to believe it could be the crank position sensor. I know sensors do start to act up once it gets hot.

I have attached the scan file and config file for hp tuners. Let me know what you guys think!

 

The correct firing order for my engine should be 1-8-7-2-6-5-4-3

the first length of numbers from this scan show

6-7-2-4-6-0-2-5-7-1-3-5-7-1-4-6-0-3-5 and on. It seems to be just random

 

Missfire sometimes. It was cam position sensor. I replaced and run fine. No missfiring. You might want try with cam position sensor if it same. You
Always can return it back to the store.

 

Did you have it re-tuned after these mods??? If not, then there is your answer.

Just because you tell a tuner what you are installing does not mean he will get it spot on in the first shot especially when dealing over the internet and not actually seeing your vehicle. Even with data logs some times they miss things. It's best to take it to your tuner and let him look at it. That way he can focus solely on your vehicle.

All though routine maintenance never hurts, just throwing parts at it blindly is a crap shoot and the odds will not be in your favor. If you don't have a check engine light on or show any pending codes then there is nothing to point you in the direction of replacing parts.

 

Yeah, it was tuned, but not in person- it was a mail order tune. I'm going to look at my crank sensor, if there is nothing obviously wrong with it that I can tell by eye then I will most likely take it to the tuner at that point.

I've been trying to avoid the "throw parts at it to fix it" mentality. The only thing I have replaced so far (that I paid for) is the spark plugs and wires.

 

As I said typical maintenance stuff never hurts. Usually when a cam or crank sensor goes bad you get a code. You will also see issues with it on the counter under live data.

You can try a crank relearn and see if that helps with the misfire. Basically the computer recalibrates it self to learn the firing order and and the small veriables it will see between firing each cylinder. My bet would be that the tuner make's a few small changes to your idle tables when AC is on and you will be good to go again.

A modified converter is usually lighter, as a result it can throw off what the computer is used to seeing especially if the timing tables have been modified. There are several tables a tuner can adjust that would help fix an idle issues you might be having.

Mail order can be tough sometimes especially with forced induction so at least let him take a look at it since he offered to help. I am sure he will get you steered in the right direction. If the normal stuff they usually use doesn't work he may be able to pin point an issue to a specific part that is not functioning correctly.

Any chance you checked the compression ratio to verify your motor is healthy???

 

Good info, thanks for the response. I thought I did check the compression, but I ended up not having time to. I will definitely get that checked. I work out on oil rigs, so I've been away from the truck for a week now. Would low compression only show symptoms at operating/hot temperatures?

It seems my problem actually exists whether or not the AC is on. The problem exists when the engine is at full temp and it is hot as ***** outside. I have an oil leak that I have been trying to tackle (which I think is located from the passenger side oil pan to engine surface, but it might be coming from somewhere else). I'm wondering if this oil has eventually seeped into the crank position sensor, which over time will cause it to read worse and worse... and also when at full temp and its hot outside, the oil is able to more easily find its way into the sensor..Making it run worse than it did when it was started up from a cold state

Anyways, I'm going to check compression and also see where that oil leak is coming from- and if it is going into the crank pos sensor. I will keep you guys posted! It probably wont be for another 5 days or so

 

I had my brother check the crank sensor. It looked fine.

Compression test will be done when I get back in town (4 more days)